AMBIENT-TEMPERATURE SYNTHESIS OF NEW LAYERED ALPOS AND GAPOS IN SILICA-GELS

A method for synthesising open-framework phosphates under less-severe conditions than those employed in conventional solvothermal processes is described. Two new layered aluminum phosphates containing pyridine and imidazole templates and their gallium analogues have been grown in silica gel at room temperature, and the structures determined by sing le-crystal X-ray diffraction. Crystal data: general formula (C5NH6)[M( HPO4)(2)(H2O)(2)] triclinic, space group P (1) over bar, lattice param eters a = 6.994(1), b = 7.2208(7), c = 12.114(1) Angstrom, alpha = 105 .080(8), beta = 104.85(1), gamma = 90.39(1)degrees when M = Al; a = 7. 056(1), b = 7.315(1), c = 12.165(1) Angstrom, alpha = 105.32(1), beta = 105.49(1), gamma = 90.25(1)degrees when M = Ga. General formula (C3N 2H5)[M(HPO4)(2)(H2O)(2)], monoclinic, space group C2/c, a = 21.893(1), b = 7.1830(3), c = 6.9890(5) Angstrom, beta = 104.164(5)degrees when M = Al; a = 22.002(2), b = 7.262(1), c = 7.047(1) Angstrom, beta = 105 .11(1)degrees when M = Ga. The four structures are closely related and contain MO6 (M = Al, Ga) and PO4 polyhedra Linked to form corrugated layers. The pyridinium or imidazolium cations occupy sites between the se layers and are linked through hydrogen bonding to one or two adjace nt layers, respectively.